Radio frequency (e.g., microwave) antennas are designed to transmit and receive radio frequency (RF) signals from an attached RF radio to another RF antenna with another RF radio attached. The RF radio and antenna are attached through a waveguide that has an interface where the two meet. This waveguide interface is critical to the quality of the RF signal. In addition to proper alignment between the waveguide of the antenna and the RF radio, the contact between the mating surfaces surrounding the waveguide is crucial. The surfaces must make contact in order for electrical continuity to be established between the surfaces surrounding the waveguide. This continuity is needed so that the waveguide in the RF radio and the waveguide in the antenna act as a single continuous waveguide so that the RF signal can properly propagate.
In a typical design, referred to as “direct mount,” an antenna assembly is mounted to a pole on a building or a tower using brackets. An RF radio enclosure (called an outdoor unit (ODU)) is mounted to a mounting plate of the antenna assembly. The antenna assembly has a feed head that is the RF interface to the ODU. The ODU has an antenna port which is the RF interface to the antenna. The surfaces surrounding the waveguide of the antenna feed head and the ODU antenna port must be in contact with each other to ensure proper propagation of the RF signals. The antenna feed head and the ODU antenna port are typically comprised of rigid metal parts.
Hence, it is necessary to account for tolerances in the assemblies when designing the mounting of the ODU to the antenna assembly to achieve electrical continuity across the parts. If the interface is rigid between the antenna feed head and the ODU antenna port then the tolerances must be absorbed between the mounting points of the ODU and the antenna assembly in order to ensure that the surfaces surrounding the waveguide of the antenna feed head and the ODU antenna port are in contact with each other.